Use caution when selecting ETF products that track narrow market segments; these products are considered risky and therefore require more evaluation. (investopedia.com)
For some merchants in narrower markets, you can get huge bonuses of 20 to 30 miles per dollar. (rewardexpert.com)
I suppose if you appreciate fine things, you might enjoy selling them too, but that's a very narrow market. (remonline.com)